6.4 – NOTES Solutions, Suspensions, and Colloids

B.1 Physical Properties of Water The Earth is unique because it has so much water. 70+% of Earth's surface is covered with oceans of an average depth of 3 km Matter Anything that has mass and takes up space  

Physical property Properties of the senses – can be observed without changing the make- up of the substance   Density The measure of mass in a given volume The formula for density is D = M V The density of water at 25 0C is 1.00 g/ml

Freezing point of water is An unusual property of water is that solid water is less dense than liquid water   Aqueous solutions- solutions that are dissolved in water NH3 (aq)  shows its aqueous solution Pure water is clear, colorless, odorless, and tasteless, which are physical properties

B2. Density Practice Problem: In the foul water lab, you observed that coffee grounds settled to the bottom of the water sample, whereas oil floated on top. Explain this observation in terms of the relative densities of coffee grounds, water and oil.   Highest Density  Coffee Grounds  Water  Oil  Less Dense

Mixture Two or more things mixed together that can be separated without losing individual properties These can be separated by physical means, without a chemical reaction

Heterogeneous mixture Composition is not uniform throughout Ex. Muddy water Suspension Particles are large enough to see and settle to the bottom, can filter

Colloid Particles are small enough to stay suspended in liquid and small enough to not see, can’t filter Milk is a colloid Other Examples; Jello, Glue Dissolving A process when crystals separate into particles so small they cannot be seen at high magnifications In a heterogeneous mixture, the particles are large enough to reflect light

Homogeneous mixture Composition is uniform throughout Solutions The only type of homogeneous mixture The particles in a solution are small enough that they cannot reflect light and cannot be filtered Solutions are made of two parts Solute – what gets dissolved Solid – Salt in water Liquid – Alcohol in water Gas – Carbon dioxide in water Solvent – what does the dissolving, usually liquid or gas

Solutions and colloids look very similar- you cannot see particles in them. The only way to tell the difference is to perform the Tyndall Test Positive Tyndall Test Negative Tyndall Test